


My Rival Seduced Me into a Relationship

by Mikazuki_Nika



Category: Magic Kaito, 名探偵コナン | Detective Conan | Case Closed
Genre: Fake/Pretend Relationship, Fluff and Humor, KaiShin Secret Santa 2020, M/M, Mild Hurt/Comfort, Post-Black Organization Takedown (Meitantei Conan), Post-Canon, Post-Conan Kudou Shinichi, With A Twist
Language: English
Status: Completed
Published: 2020-12-20
Updated: 2020-12-20
Packaged: 2021-03-11 01:48:53
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 6,134
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28187172
Author URL: https://archiveofourown.org/users/Mikazuki_Nika/pseuds/Mikazuki_Nika
Summary: “My mother is harassing me, so please go out with me for one month.”“...What?”The absolute last thing Kaitou KID expected to hear from his long-time rival (short-time friend?) Kudou Shinichi was anything likethat.An indulgent Christmas story written for the KaiShin Secret Santa 2020 event!
Relationships: Kudou Shinichi | Edogawa Conan/Kuroba Kaito | Kaitou Kid
Comments: 10
Kudos: 261
Collections: dcmkkaishinevents kaishin secret santa 2020





	My Rival Seduced Me into a Relationship

**Author's Note:**

> You may consider this a post-canon story, i.e., the Black Org has been wiped out and Shinichi returned to his real body a few months ago.

**Prologue**

It began with a lie.

“My mother is harassing me, so please go out with me for one month.”

“...What?”

The absolute last thing Kaitou KID expected to hear from his long-time rival (short-time friend?) Kudou Shinichi was anything like _that._ He stood slack-jawed, poker face slipping as the renowned Detective of the East stared at him calmly and intensely as always.

“I said, ‘please go out with me for one month,’” he repeated, straight-faced.

“No, no, no,” KID backpedaled, hands flailing. “Wait. Dating? With _me?_ You don’t even know my real name!”

“You don’t have to tell me,” Shinichi protested. “You can just use an alias.”

The thief deadpanned. “My, how generous of you…” 

“And I think you’ve known for a long time that I don’t have any intention of turning you in to the police.”

KID’s gaze narrowed suspiciously. “But you still intend on capturing me.”

“Well…” the detective shuffled awkwardly. Coughing into a fist, he continued, “My only request is that you live at the Kudou mansion for the duration of our relationship.”

_“Excuse me?”_ KID sputtered. “Not only do you want us to start dating, but you also want us to live together?!”

The phantom thief watched in horror as the detective’s ears turned pink and he managed a nod. In the awkward atmosphere that followed, only the crisp winds of autumn moved between them. KID found himself flustered and forced to improvise in front of his favorite critic - and not for the first time.

Having already finished checking the jewel from tonight’s heist for traces of Pandora, there was nothing left for him to do except escape, but the absurdness of the situation kept his feet rooted to the concrete. 

“Umm… I’m getting cold, so could you please tell me your answer now?”

The thief snapped out of his stupor, and all of a sudden, it all made sense. He scoffed. “Ahh, okay, okay, I see what’s going on here now. This is a joke, right? Or did someone on the task force come up with some kind of insane plan to capture me by forcing you to be bait? Wait, are you sick?” he asked, rushing forward to grasp Shinichi’s shoulders with a sense of urgency. “Just tell me what’s wrong, Meitantei. I’m Kaitou KID, you know! I’m a guy, not that cute Mouri girl you’re always with!”

Though Shinichi made no move to release the grip on his shoulders, he turned his head away when the thief drew too close for comfort. KID, for his part, seemed to slow down when Shinichi’s face grew impossibly red. “That… isn’t a problem,” he mumbled embarrassedly.

“Which part?”

“The fact that you’re a guy… or Kaitou KID, for that matter…”

“Oh.”

“And Ran and I are just friends…” 

_“Oh.”_

Stunned by the news, KID hardly registered Shinichi taking the chance to search his expression. There was an annoyed huff, and in the next moment, his senses were flooded by the detective’s presence. In a fit of annoyance mixed with boldness, Shinichi had suddenly drawn closer to him, close enough to count his eyelashes and smell his cologne.

There was a thigh wedged between both of his own, causing the thief to stiffen and his eyes to blow wide open. His heart jumped up to his throat, its beat pounding in his ears the way it did whenever he had to freefall before activating his glider. He could feel his face beginning to redden much as the detective’s had earlier, and his view was filled with his sapphire-like eyes.

Shinichi stared unwaveringly at him.

“I think you’re misunderstanding something here, KID.”

He swallowed thickly. “Uhhh-”

In one, long breath, the detective pressed, “Ever since things between Ran and myself fell apart, my mother has been harassing me to no end about a new relationship. When she comes home this Christmas, I’d like to end this nonsense once and for all. Hattori can’t possibly live at the Kudou manor for a month because of school, and after pinning all of your past heist locations on a map, I’ve determined that you live here in Tokyo. As the only other single person in my age group that I trust, I had no choice but to ask you to be my fake boyfriend for one month.”

Abruptly, as if he were running out of gas, the tension in Shinichi’s body relaxed incrementally. A strange look came to his face, like a cross between a smirk and a genuine smile. “Besides, having me owe you a favor, especially one on this scale, sounds like a great idea, doesn’t it?”

Unfortunately for him, the thief’s brain had stuttered to a complete stop upon hearing the word “trust” fall from the detective’s lips. The word echoed around in his now-empty mind like the DVD video logo bouncing around a TV screen.

When the logo hit the corner, “Um, yeah.”

Shinichi was out of his personal space before he could even blink, grinning boyishly. He turned to leave, but not without saying, “Great. See you at home then. Bring your necessities with you.”

He was gone by the time KID’s mind could catch up with his mouth and everything else that had just happened. Jolting out of his daze, the thief gasped.

“D-Did… Did I just accidentally say ‘yes’ _Kudou Shinichi_ being my fake boyfriend?!” Grasping his head with both hands, Kaito screamed. “I meant to say ‘yes’ to his question, not the dating thing!” His hands fell to his mouth as he stared wide-eyed at the concrete rooftop.

Grimly, and mentally berating himself the entire time, Kaito tells himself, “I have to fake-break up with him.”

**Week I.**

**Setting Boundaries**

As if somehow aware of his intentions, Shinichi gave Kaito zero room to mention anything about breaking up that night. Instead, he showed the tense and awkward thief (who was loosely disguised) to an empty bedroom in the house not far from his own and told him to make himself at home. Inside, while Kaito scanned his room for spy equipment, he tried to hype himself up.

“Okay, we’ll just tell him directly that this is all a big misunderstanding,” Kaito murmured to himself, running a hand across the crown moulding. “It’s true that I said ‘yes,’ but it was a reply to his question about owing a favor… having the Great Detective owe me big time is always a blessing, after all…”

Straightening, the thief looked around the room in confusion. It had appeared innocent enough when he first walked in, but-

“There’s no hidden cameras? No bugs? _Nothing?”_ he let out in disbelief. 

Gobsmacked, he considered checking the entire room again when his duffle bag, sitting ominously on the corner of the bed, caught his eye. 

_‘If you were planning to turn him down, why did you bring your stuff?’_ a voice in his mind asked mockingly.

Swallowing thickly, the thief felt his face begin to heat up and decided to leave the room before that train of thought got any further. 

Downstairs, he found the majority of the manor’s lights off. This was not alarming, for Kaito knew it was well past three in the morning considering he had let himself be dragged into this entire charade just after a heist. Shinichi himself had left Kaito alone with the intention of letting him rest, it seemed.

And yet he found the detective awake, in the manor’s study.

“KID?” he blinked, upon hearing the heavy door swing open. “I thought you would be sleeping. Is something wrong?”

_‘Well, a lot of things, but-’_

“Post-heist adrenaline,” Kaito lied smoothly, faking an embarrassed chuckle. “I _am_ tired, but usually after a heist I’m too wired to sleep right away,” he explained. “What are _you_ still doing awake?” the thief asked.

Shinichi’s crinkled brow relaxed upon accepting his explanation, and he held up a stack of papers. “Just a few things I need tomorrow morning. I’m planning to sleep after I finish, but… Well, this timing is good enough. Take a seat, KID, and let’s talk about how this co-habitation will work.”

The thief tensed, approaching the set of armchairs around the fireplace and slipping into a seat like a guarded cat. Shinichi rose from his place at the desk and took the armchair across from him. The Kudou manor was large and especially prone to cold temperatures in the autumn and winter seasons, but the fireplace and the carpet were warm.

“First of all, I’d like to start off by mentioning that it isn’t my intention to interfere with your daily life,” Shinichi said seriously. “I don’t know what kind of lifestyle you lead during the day, but I’m not expecting you to give up on things like attending school or hanging out with your friends or part-time work while you’re living here. I will continue living my life as I have until now as well, so I hope you will think of the Kudou manor as your home rather than a jail place.” 

Kaito exhaled under his breath. Based on the detective’s words, the life of ‘Kuroba Kaito’ would be mostly unaffected by this arrangement - but, there was no way he could plan a heist while inside the Kudou mansion. If a new target came to Japan sometime this month, he had no choice but to leave the majority of the planning to Jii-chan.

Locking gazes with Shinichi, he asked, “If that’s the case, then what do you need me for?” 

The detective smiled - almost apologetically. “I just want a bit of your time over this next month. As I mentioned earlier, my mother has been badgering me nonstop about a relationship, but I know she’s doing it with good intentions. I definitely need you here for Christmas.”

“And throughout the rest of this month?” Kaito prompted.

“If you happen to be home when my friends visit, I hope you’ll help me in convincing them as well. My mother might expect me to pull this kind of stunt, and I expect she’ll start asking questions - especially to Ran.”

At this, the pair of young men fell silent - Shinichi allowing the thief some room to think and Kaito finding convincing the detective’s ex-girlfriend to be a daunting task. That said…

Kaito took in a slow breath, making sure his poker face was firmly in place despite the baseball cap on his head obscuring his facial features, before asking, “And how, exactly, do you expect us to convince everyone?” Steeling himself, he managed a smirk. “Should I kiss you, Meitantei?”

To his pleasant surprise, the detective’s cheeks colored rosily. He was _not,_ however, expecting Shinichi to duck his head slightly and look at him from under his lashes. Pouting, he huffed, “Ba’aro.”

_Doki!_

Kaito flinched, scrambling internally. _‘Wha- What? Wait, ‘doki?!’ No, no, no - no doki! No doki!’_

Oblivious to the thief’s panic, Shinichi continued, “I’m not expecting you to do anything you’re not comfortable with. Fortunately, I’m not someone who is particularly… flashy,” he finished awkwardly.

“So you’re saying we’ll be fine even without public displays of affection?” Kaito clarified. 

“Yes,” Shinichi nodded. “It will be enough if we seem close. With that said… I can’t keep referring to you as ‘KID,’ so what should I call you?”

Kaito recognized the change in topic for what it was: an attempt to keep either of them from feeling overwhelmed and awkward. Accepting it gracefully, he replied, “‘Kaito’ is fine.”

A strange look came over the detective’s face at that.

“...What is it?” Kaito prompted.

“Sometimes I forget what a strange sense of humor you have.”

**Week II.**

**Gaining Trust**

True to the detective’s word, Kaito was allowed to come and go from the Kudou mansion as he wished. Thus, he was able to continue attending school in Ekoda as usual, but because there was still a considerable amount of distance between his hometown and Beika, he found himself making excuses left and right to Aoko as to why he was never to be found at home.

The fiery brunette stood before him now, hands on her hips with a determined look on her face. Kaito mentally apologized to Jii-chan before saying, “To be honest, Jii-chan’s health isn’t that good right now. I’ve been crashing at his place lately to help him, especially with the bar.”

Aoko deflated, her annoyance immediately forgotten as her expression melted into worry. “Why didn’t you say so sooner? Aoko will bring food over tonight!”

Kaito smiled wobbly. “Sorry, I just didn’t want to worry you. And don’t worry about the food; Jii-chan’s neighbor has been helping us out a lot,” he laughed.

“Oh, okay… Aoko understands. If you miss a day of school for Jii-chan, Aoko will take notes!”

Kaito grinned. “Thanks, Ahoko.”

“Don’t mention it, Bakaito.”

The most surprising aspect of his cohabitation with the Great Detective, however, had to do with the detective himself. Kaito returned from school in Ekoda at regular intervals, found the manor empty, and waited for Shinichi’s return while busying himself with schoolwork or magic practice. Occasionally, he stopped by his house after classes (taking the time to walk home with Aoko to keep her appeased) in order to care for his doves. Still, the manor would be empty upon his return.

And even though he continued to disguise himself casually - a baseball cap here, a fake face there - he never found any bugs placed around the house. It seemed the detective was serious about not turning him in to the police - a dangerous thought that made Kaito relax incrementally.

Shinichi came home at irregular times over the week and would often find the thief in the study. Kaito wisely decided to keep it a secret that with all the free time he had been given to explore the shelves of the study, he had found the Kudou family photo albums.

“Hey,” Shinichi would greet quietly, managing a smile.

“Hey,” Kaito would greet back.

Thus, during the second week, the thief came to a decision: Kudou Shinichi’s lifestyle was entirely messed up.

“Meitantei,” Kaito began, “You live like this?”

Shinichi glared at him over a steaming cup of coffee. “I don’t want to hear that from someone leading a double life. You’re up late just as often as I am.”

Kaito winced, deciding to brush past that valid statement. “True, but you’re on a whole different level, Meitantei. What do you usually do after school?”

Shinichi steepled his fingers, eyes drawn to the flames dancing in the fireplace. “Sometimes I’m helping the police, sometimes I’m doing schoolwork.”

“‘Schoolwork?’” Kaito echoed, already aware the detective met with unfortunate cases nearly every day. 

Shinichi sighed lightly, eyes closing and a graceful smile pulling at his lips. “‘Kudou Shinichi’ went missing for a long time, after all. I have quite a bit to catch up on if I want to attend university alongside my friends next spring.”

Kaito fell silent at this, various realizations coming to light. Unlike himself, Shinichi couldn’t live both of his lives simultaneously. Couldn’t attend high school, couldn’t investigate cases freely, couldn’t associate with his friends. Kaito had one foot in both the lives of ‘Kuroba Kaito’ and ‘Kaitou KID,’ and that, of course, came with its own struggles, but he couldn’t imagine leaving ‘Kuroba Kaito’ behind for years. 

_‘Right now, Meitantei is trying to catch up to a world that has already moved on without him.’_

The following morning, Kaito stopped looking for bugs in his room. Going downstairs for breakfast without a disguise was worth it just to see Shinichi spill his beloved coffee all over the kitchen counter. ****

**Week III.**

**Take Care of Him**

“You’re not Shinichi.”

Kaito stood frozen in the entryway into the Kudou manor, having opened the door without thinking. On the other side was Mouri Ran, who had taken one look at him before narrowing her eyes in suspicion.

_‘Of all times, why now?!’_ Kaito screeched internally. _‘The Great Detective isn’t home yet!’_

Realizing he had yet to respond, Kaito jolted into action. Smiling, he stepped aside to let the suspicious young woman inside. “You’re right, I’m not Shinichi,” he said simply. “My name is Kuroba Kaito. You must be Mouri Ran-san.”

He saw her shoulders tense as she caught onto several things at once: the intimate way he had referred to Shinichi, the fact that he was aware of who she was, and the fact that he had been the person to open the door. She said nothing, however, as she swapped her shoes out for a pair of slippers and left her schoolbag leaning against the wall.

After asking whether she preferred tea or coffee, Kaito joined her in the sitting room and forced himself to look comfortable. “You’ve probably figured it out already-” He reached over the table to turn the TV’s volume down. “-But Shinichi isn’t home yet. Should I give him a call and ask him to hurry home?”

_‘I already texted him while I was in the kitchen, but she doesn’t have to know that,’_ he mentally winced. 

“No, that’s okay,” Ran replied. “I half-expected him not to be home anyway. I would be on my way, but…” she gave him a meaningful look.

Kaito bit his lip, deciding to take the plunge. “I’m sorry we haven’t had the chance to meet in a better setting yet. As I said earlier, my name is Kuroba Kaito. I’m…” he hesitated, feeling his cheeks redden against his will. “Shinichi and I are dating.”

Silence.

Fearfully, Kaito looked up to find a cup of coffee paused halfway along its route to Ran’s lips, her jaw hanging open in shock. “‘D-Dating?!’” she echoed a beat later, voice skipping an octave. “You and Shinichi?!”

Expertly playing the part of a shy lover, Kaito nodded bashfully.

He wasn’t expecting her eyes to light up and a grin to begin tugging at her O-shaped mouth. “Since when?!” Ran demanded, gasping in excitement.

“Just a few weeks,” Kaito replied, feeling hopeful at her positive expressions. “But we’ve known each other for a few years now.”

“A few weeks…” Ran repeated. Then, a hand came up to smother a delighted smile. “So you’re the one…!”

“I’m sorry?” Kaito prompted, not understanding.

“Oh, nothing!” She waved a dismissive hand. “More importantly, tell me everything! Who confessed?”

“I did,” a new voice answered from the doorway. The chatting pair lifted their heads simultaneously to find Shinichi casually leaning a hip against the doorframe, attempting to disguise the fact that he ran all the way here.

_‘Nice timing, Meitantei!’_

“Shinichi! Why didn’t you tell me you had a boyfriend?” Ran grinned. 

“Because Sonoko has influenced you too much,” Shinichi huffed, stomping into the room with an air of annoyance. He took a seat near Kaito. “Look at you already trying to piece together what happened.”

“Doesn’t that make her more like a detective?” Kaito chirped up slyly. “Maybe _you’re_ the one who’s been a bad influence.”

Shinichi heaved a troubled sigh. “Not you too, Kaito. Whose side are you on?”

Ran’s gleeful gaze ping-ponged between them, following the conversation closely.

“What do you mean?” Kaito smiled innocently. Cutely, he tacked on an impish, “I’m always Shinichi-kun’s ally~”

Shinichi shook his head as if giving up. “More importantly, what are you doing here, Ran?”

The brunette’s expression soured slightly at this. “You promised we’d walk home together today, but you disappeared after school!” She crossed her arms. “I was going to give you a piece of my mind, but I’ll let it go for now because Kuroba-kun has been kind enough to keep me company.”

“I’m sorry,” Shinichi apologized. “I got a call from the precinct and forgot to let you know ahead of time.”

Ran huffed, “I’m sure you got distracted by the case as soon as you heard the details, you mystery otaku.” Turning to Kaito, she said, “If Shinichi gives you a hard time, let me know and I’ll knock some sense into him! I’m a karate champion, you know.”

Kaito lit up. “That’s reassuring!” 

Shinichi slumped further down into his seat. “Great, now you’re conspiring against me together? At this rate, I’ll never catch a break.” He then stood up, excusing himself with, “Let me go grab a cup of coffee for myself too.”

The atmosphere of the room shifted as soon as he left. Kaito sat a bit straighter, already aware that things were going _too_ well. Prepared for threats or even bribe money, he met Ran’s gaze.

“Shinichi might have already told you this, but he and I dated for a short while too,” she began. Her smile turned bittersweet. “Things didn’t really work out. I needed more attention than Shinichi could give at the time, and Shinichi needed someone who could support him no matter what he was dealing with.”

Kaito fought to keep his jaw from dropping in surprise, having not expected her to open up in this way.

“You can’t bring yourself to ask for help from someone you’re trying to protect,” she continued. “That’s why I hope you won’t let Shinichi try so hard by himself all the time. Maybe instead, you can become someone capable of standing by his side.”

Stunned, Kaito could do nothing but nod once, silently. Something inside of his heart was shifting ever so slightly - a realization that he wasn’t sure he wanted to make just yet. Even so, there was an inexplicable feeling of warmth, and…

Loneliness. 

“I’m sorry,” Ran laughed embarrassedly. “I’ve only been saying strange things so far…” Her tone was playful, but her raised fists were anything but. “Just know that if you hurt Shinichi in any way, I won’t forgive you!”

Kaito blinked in surprise for a moment before chuckling in acceptance.

“Of course.” ****

**Week IV.**

**Showtime**

The rest of the week flew by between end-of-term exams and heist planning with Jii-chan. Kaito’s prediction a few weeks ago had been on the mark - there would be a new Pandora target showcased in Tokyo just after Christmas. In the meanwhile, he had only a few days left to prepare for the arrival of Shinichi’s parents.

“Not to complain, but this is _stressing me out,_ Kudou!” Kaito cried over the top of an enormous Christmas tree. He was hanging upside down from the second floor, legs trapped between the banisters in the open corridor as he attempted to place a light-up star on the top. “You didn’t mention anything about a Christmas _party_ before!”

Shinichi rolled his eyes, perched atop a ladder and delicately placing luxurious ornaments on the tree’s branches. “Complaining is _exactly_ what you’re doing, Kuroba. Let’s just hurry up and finish with this so we can have lunch. We still have to put up the mistletoe and line some garland along the banister.”

“Lunch that _I’m_ going to have to make! If anyone else saw what I go through these days, they’d think I was your maid, not your boyfriend.”

Shinichi rolled his eyes again, already used to Kaito’s woe-is-me dramatics. “I already told you that you didn’t have to do all that,” he huffed, mostly to himself, but Kaito could see a smile tugging at his lips.

“We’d die if I let you do all the cooking around here, what with your insane schedule,” Kaito pointed out, straightening up and righting himself on the second-floor landing. He came partway down the stairs to stand near Shinichi as he finished placing the ornaments. “The hospitality here is horrible, really.”

The detective shoved the container of ornaments in the sniffling magician’s face. “You’ve gotten bolder now that you know I won’t be turning you in, thief.”

Kaito accepted the container, grinning widely but remaining silent as Shinichi climbed down the ladder.

Thus, between finishing the semester, preparing for the party, making sure Shinichi ate more regularly and keeping him company in the late hours he used on makeup work for school, and planning a heist, Kuroba Kaito was a very busy man. 

But… he’d be lying if he said he wasn’t having fun.

_‘The Great Detective has always been cool in front of me, but now that I know how much work he is putting in behind the scenes, I can’t leave him alone.’_

Carrying those feelings in his chest, Kaito greeted the day of the Christmas party cheerfully. He was _not,_ however, expecting Kudou Yukiko to stare into his face before recognizing him.

“Kai-chan?” she asked, tilting her head curiously. Shinichi paused in his conversation with his father to echo the endearment in surprise. “It _is_ you!” she gasped gleefully. “What a surprise! How are you doing? How is Chikage?”

Kaito reddened, half in embarrassment and half in panic. “I-I’m fine, mom’s fine too. Still traveling. Um- I’m sorry-”

“You don’t recognize me,” Yukiko deflated, stepping out of his personal space to place a troubled hand on her cheek. “Hmm, yes, I suppose you must have been too young to remember. We’ve met once before - I was your father’s student!”

“‘Student?!’” Shinichi repeated in shock.

“Yes!” Yukiko answered cheerfully. “Look dear, it’s Kuroba-sensei’s son.” 

Yuusaku’s eyes flashed with recognition before a knowing smirk rose to his lips. “That’s right, he did have a son Shinichi’s age.”

Kaito wasn’t sure what to make of that gaze but alarms were ringing in his head already. He was relieved when Yukiko ushered them all towards the sitting room, exclaiming compliments over the Christmas decorations all the while.

_‘She doesn’t know Shinichi almost cracked his head open trying to hang up that mistletoe.’_

“So,” Yukiko began when they were all settled. “How did you two become friends? It’s really surprising how small the world can be sometimes!”

“It was at a Kaitou KID heist, actually,” Shinichi answered smoothly, beginning the story they already had prepared. “I was there as a favor for another detective who couldn’t attend at the time and met Kuroba there.”

“As a magician and a family friend of the Inspector leading the Kaitou KID Task Force, I sometimes show up at heists as an advisor, trying to predict KID’s next move,” Kaito continued. He felt Shinichi’s gaze on the side of his face, aware that he had caught onto the extra information Kaito slipped in regarding the Nakamoris.

“Is that so?” Yuusaku hummed politely, but his eyes were still glowing.

“Fascinating!” Yukiko added, her smile unreadable.

Kaito momentarily closed his eyes. _‘Jii-chan told me Oyaji had a rivalry with a mystery novel writer… this cannot be happening right now. This entire family knows I’m the current Kaitou KID.’_

“Actually, there’s something we have to tell you,” Shinichi began. Crying on the inside, Kaito did his best to keep smiling warmly. “As of last month, Kuro- _Kaito_ and I have started dating.”

Yukiko’s grin only grew wider, like the cat that caught the canary. “Dating!” she breathed. “Shin-chan, that’s _wonderful_ news! Don’t you think so, dear?”

Yuusaku smiled to himself. “I’m definitely a little surprised, but yes, that’s wonderful news. Your mother was worried after…”

“Ran-san?” Kaito filled in, appreciating his attempt to spare his feelings. “I understand. I met her a few weeks ago. We bonded over our shared sufferings for this idiot detective.”

Shinichi had the gall to look offended, but Kaito could see the excitement over their success in convincing the Kudou couple of their relationship shining in his eyes. 

Although he had a feeling it had gone a little _too_ well… 

Evening fell and before Kaito knew it, the manor was full of guests. The Mouri father and daughter, the Suzuki heiress, the Detective Boys (who cried “Shinichi-niisan!” in excitement as soon as the detective had opened the door) and the old man who chaperoned them, the Detective of the West and his childhood friend… And Kaito needed to meet them all. 

A sense of dread washed over him as he stepped into the noisy sitting room, now transformed with combined efforts in the afternoon into a small party hall. Foldable tables lined the walls with catering from KFC, and the coffee table that used to sit comfortably between the sofas was cleared away. 

“Ready?” Shinichi asked at his side.

The magician grinned. “It’s showtime.”

The next few hours seemed to go by in a blur as Kaito was whisked from one group of people to the next, introduced by Shinichi as his boyfriend much to the surprise of almost every guest. The Osakan detective was still yelling even though Kaito had long gone on to meet the next group. Haibara Ai had been unable to contain a knowing smirk as soon as she’d seen him. And once introductions were over, he found himself trapped between the girls - Ran, Sonoko, and Kazuha - for questioning. 

At some point, Sonoko leaned in slyly, cupping a hand around her mouth. “So? How is it? Be honest, are you in love with him yet?”

Kaito blinked in confusion, cheeks reddening slightly. “I’m sorry?”

“The one month trial period!” Sonoko exclaimed exasperatedly in a stage-whisper.

“Wait, wait,” Kazuha cut in. “I dunno what you’re talkin’ about!”

“I haven’t told Kazuha-chan the story yet,” Ran chirped up.

_‘What story?’_

Sonoko crossed her arms, smiling triumphantly. “About two months ago now, Shinichi-kun approached Ran and me for advice because - and get this - he wanted to _confess_ to the person he likes!” she gushed. “Man, it was so satisfying to see him that embarrassed.”

“Sonoko!” Ran scolded, though the smile on her face betrayed her true feelings. Sonoko only snickered in response.

“And? What was that about a one month trial?” Kazuha prompted excitedly, clearly invested in the story.

Kaito tensed, a feeling of foreboding washing over him in waves. He had a feeling he wasn’t supposed to hear this information, but he was internally grateful for Kazuha’s presence tonight. Thanks to her, Kaito didn’t have to give away the fact that their relationship is fake by pressing the girls for information.

“Oh that,” Sonoko calmed. “It’s that thing that some people do when they confess to someone they might not have spent a lot of time with.”

“I think…” Ran put a hand to her fist. “Shinichi had asked, ‘What if the other person turns me down,’ right?”

“Yes, exactly,” Sonoko nodded. “So I told him, ‘If that happens, ask them to go out with you for one month because their feelings might change.’”

Kaito went still.

“Now that you’re mention’ it, I know a couple like that,” Kazuha said thoughtfully. “A girl at my high school confessed to a senpai she really admired a year ago or so now, and he was gonna turn her down, but she convinced him to try datin’ for a month and who woulda thought - they’re still together today.”

Ran said something about romance being all about timing, but Kaito couldn’t hear her. His mind was full of Shinichi’s voice on that rooftop in November.

_“My mother is harassing me, so please go out with me for one month.”_

Suddenly, several things were clear at once. He had been confused about the Kudou couple’s reactions to hearing the news that they were dating, but it made a lot more sense if Yukiko _hadn’t_ been harassing her son about finding a new love the way Shinichi had claimed. Meaning there was no need for him to make Kaito his fake boyfriend in the first place. So then, why had he asked him out?

_‘If Suzuki’s story is to be believed, then it’s because…’_

Across the room, Shinichi paused. He turned, feeling someone’s stare on his back, and met Kaito’s gaze. The detective was about to smile curiously as if asking ‘What’s wrong,’ but the smile died on his lips before it could even bloom. Kaito’s expression was distant and unreadable. Shinichi searched for the cause, immediately zeroing in on Ran and Sonoko standing nearby.

_‘Oh.’_ Shinichi swallowed thickly. He could feel warmth flooding his face in a combination of embarrassment and humiliation, but bravely forced himself to meet Kaito’s gaze.

That night, Kuroba Kaito disappeared from the Kudou mansion.

**Epilogue**

**My Rival Seduced Me into a Relationship**

“Should I assume you’ve broken up with me?”

Kudou Shinichi’s voice is as cold and as light as the winter around them. This is certainly not the type of weather to be standing on a rooftop, allowing the freezing winds to cut through their clothing, but it had started on a rooftop and here it would end, Shinichi decided.

Kaitou KID did not turn at the sound of his voice, choosing to stare up at the moon instead. Shinichi’s expression crumpled at the sight, aware he was seeing Kuroba Kaito standing there in KID’s clothes, not the persona he had created. It made him look young. And with the gentle moonlight streaming over him, it made him look fragile.

“Were we really even dating in the first place, Meitantei?” he asked quietly.

Shinichi’s fists curled into balls at his sides. “I’m sorry,” he let out, a wretched expression on his face. “I lied about needing a fake boyfriend.”

“Why?”

The detective’s gaze flicked up from the concrete rooftop under his feet to the phantom thief that was now facing him. With his back against the moonlight, it was hard for Shinichi to see his expression.

“I panicked,” Shinichi admitted. “I thought there was no way you would accept if I asked you directly since I knew you didn’t fully trust me not to turn you in. If I asked you for help, on the other hand, you might actually consider it because, well… I know you’re a good guy,” he mumbled.

“You took advantage of my kindness.”

Flinching, the detective opened his mouth to protest before slowly letting it close again. “You’re right, I did. I’m sorry,” he repeated.

He caught movement out of the corner of his eye, looking up to watch as KID dragged a hand up to his chest. “You haven’t touched me since that day. Why?”

Shinichi swallowed, hard, his cheeks reddening deeper than the cold had already made them. “I-I…” he licked his lips and tried again. “I knew you were attracted to me, at least a little, so I wanted to distract you from the lie.” 

“Ha,” Kaito laughed flatly. “Nicely played, detective.”

Silence fell between them as Shinichi shuffled awkwardly. He wasn’t sure what he should say or do next, but-

“If you never want to see me again, I understand,” he said.

“That’s not it!” Kaito exploded, his loud voice shocking both of them. “That’s not it,” he repeated, quieter. “I just don’t understand-”

“What?” Shinichi called. “I couldn’t hear because of the wind.”

Kaito inhaled deeply, face scrunching as he lifted his face. Shinichi’s breath caught at his expression as the moonlight flooded his features. He was blushing.

“I don’t understand why you didn’t trust me!”

Taken aback, Shinichi faltered, half-smiling awkwardly. “Trust you about _what?”_

“You say you wanted to ask me out but you didn’t even trust me enough to take your would-be confession seriously!” Kaito exclaimed, closing the distance between them. He was almost nose-to-nose with Shinichi before the detective could even consider stepping back. “Ask me again.”

“...What?”

“Ask. Me. Again, Shinichi,” Kaito breathed. “Confess. Properly, this time.”

The detective’s eyes widened. Kaito’s violet-eyed gaze was swirling, searing into his memory. He wasn’t sure if the roar in his ears was the wind whirling around them or his heart pounding relentlessly.

“...I like you, please go out with me.”

“You’re lying.”

Shinichi winced, wishing he could screw his eyes shut, but Kaito’s stare wouldn’t let him go. “Yes, you’re right. I lied. I love you, please don’t break up with me.”

The next second lasted a lifetime.

Kaito’s lips pressed desperately against his own, his arms wrapping around Shinichi’s shoulders. The detective immediately embraced him, returning the kiss as best as he could despite his surprise. Kissing Kaito was like tasting sunlight, and he knew immediately that he would be addicted to the flavor for the rest of his life.

They broke apart, breathing a little heavier than before. Kaito’s hands moved from his shoulders to Shinichi’s face.

“I won’t let you steal my chance to say ‘yes’ ever again,” he murmured seriously into the space between them. “I’m in love with you too.”

Shinichi broke into a smile despite himself. “Wait, seriously? Since when? Before or after this month?”

Kaito scoffed, “Of course you’d want to know when. Stupid detectives, always ruining the magic.”

“Fine, we have plenty of time to talk about it anyway.”

The thief smiled at that, quick-changing out of his KID costume into a simple disguise and leaving hand-in-hand with the detective.

Shinichi didn’t let his hand go all the way home.

“By the way,” Kaito spoke up. “I’ll only accept your apology if you let me make copies of the baby pictures in the study.”

Shinichi stiffened.

**Author's Note:**

> Merry Christmas! I did this in a rush so please forgive my super indulgent writing if there’s any mistakes. Because this is a oneshot (albeit a long one) for the KaiShin Secret Santa event, I didn’t expand on the ideas as fully as I could have. I hope you enjoyed it nevertheless. Please feel free to screech in my comments or leave kudos! I appreciate it! :))


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